I'm sure you'll get different responses; And I am by no means an expert, but for the track I think 30mm is a bit much. for the street it's fine, but on track you should be more along the lines of 25mm. as far as the dive goes, you can throw as much rebound at it as you want, but it isn't going to make much difference. Compression is where you need to focus for that. I'm not familiar with what spring weights come in the gixxer forks, but I can tell you this. The springs in my bike are the exact recomended for my wieght, but I do get excessive dive on hard braking. the problem is there is not enough adjustment range on my clickers to control the dive. so you probably have more of a damping issue than spring issue as most oe dampers don't have a lot of effective damping range. check out the racetech website, there is a spring weight calculator to see what springs you need and you can also look up what springs you have.
In the mean time I would add a touch of preload and a bit of compression in small increments to see if you can find something that works. You can also put a wire tie loosely around the slider of your fork to see just how far it is compressing or if it is bottoming out. good luck and small changes are your friend.